An Orange County middle school teacher is in custody on suspicion of molesting four students, including a girl who says he had sex with her in a San Clemente classroom, police said. Richard Rack, a 50-year-old math teacher at Shorecliffs Middle School in San Clemente, was being held Friday on $1-million bail after an investigation that began in November escalated when Orange County sheriff's detectives learned he had had a sexual relationship with a teenage girl for two years. "The sexual relationship began when she was a student in his classroom. The sexual acts occurred in the classroom and at the girl's home," said Jim Amormino, spokesman for the Orange County Sheriff's Department.